Pittsburgh Mayor Luke Ravenstahl's challenge of UPMC's tax-exempt status creates an “adversarial climate” that makes it impossible for the city's colleges and universities to discuss increasing payments in lieu of taxes to the city, a group of school leaders says.

The Pittsburgh Council on Higher Education, which represents Carnegie Mellon University, University of Pittsburgh and eight others, said in an April 5 letter to Ravenstahl that its members won't take part in discussions with a task force created to examine financial support from the city's largest nonprofits.

“Making progress on these long-standing issues is difficult even in the best of circumstances,” said the letter, which the Tribune-Review obtained Monday. “It would be counter-productive to try to push forward in the adversarial environment that exists today.”

The Nonprofit Sector Support Task Force, which the Intergovernmental Cooperation Authority asked the city to create as a condition of passing the 2013 budget, is required to issue a report by the end of June on payments nonprofits can make to the city because they don't pay property taxes. The ICA is one of two groups overseeing the finances of the city.

Marissa Doyle, Ravenstahl's spokeswoman, declined to answer questions about the letter. “We look forward to reviewing the results of the ICA-mandated Nonprofit Task Force's efforts and hope that all nonprofits will work in cooperation with the ICA and the Task Force,” read a statement from the mayor's office.